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model. Three months post-implantation, bridging was observed for both
ABG and rhBMP-7 treatment groups. Twelve months post-implantation,
rhBMP-7 treatment group show significantly greater bone formation and
mechanical strength compared to the ABG treatment group as illustrated by
m-CT imaging (Figure 9.8) and biomechanical analyses. At all time points, the
level of bone formation in the cell-free scaffold group and MSC treatment
group were not comparable to those of ABG and rhBMP-7 treatment
groups.
70
Low levels of BMP combinations to better mimic physiological conditions
were explored by Yilgor et al.
71-73
PCL scaffolds were coated with PGLA-BMP2
and PHBV-BMP7 nanocapsules using alginate as a carrier. The nanocapsules
were stabilised onto the PCL scaffold surfaces by cross-linking of alginate
with 5% calcium chloride. An earlier study had shown that a sequential
release of BMP-2 followed by BMP-7 from their respective nanocapsules
could be achieved.
71
Nanocapsules containing BMP-2 and BMP-7 were
loaded onto PCL scaffolds with varying architecture. It was shown that co-
administration of BMP-2 and BMP-7 in a sequential manner could promote
in vitro osteogenic activity regardless of the scaffold architecture.
72
Following
these positive outcomes, PLGA-BMP2 and/or PHBV-BMP7 were loaded into
PCL scaffolds with varying pore geometry and sizes.
73
The BMP loaded
scaffolds were implanted into rats with bilateral 5 mm burr-hole pelvis
d
n
3
r
4
n
g
|
1
.
Figure 9.8 Cylindrical PCL-TCP scaffolds produced via FDM with an outer diameter
of 20 mm, inner diameter of 8 mm and height of 30 mm implanted into
an ovine segmental defect. Histological and imaging analyses of bone
defects after 3 and 12 months. m-CT reconstructions are shown next to
safranin orange/von Kossa-stained histological sections (orientation:
top, proximal; left, medial).
Adapted from Reichert et al.
70
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